A hybrid clonal neural cell line with alpha-2-adrenergic, muscarinic (cholinergic), and opiate receptors is used as a model system to explore how a variety of psychotropic drugs induce long-term effects on brain neurotransmitter receptor sensitivity. Attempts are made to directly correlate biochemical and intracellular electrophsiological measurements of receptor response to acute and chronic administrations of clonidine, morphine, neuroleptics, and tricyclic and atypical antidepressants in culture. Neurochemical indices of receptor function include drug/receptor binding, adenylate cyclase activity, cyclic nucleotide production, and guanine nucleotide regulatory protein levels. Interaction between the alpha-2 and opiate receptors is also examined.